DE 24 46 693 provides examples in the field of manufacturing stacks outside of the tool and press. This publication describes how to manufacture stacks of steel that has a thermosetting coating. EP 0 121 173 describes an approach to solving the problem in which the laminations are provided with elevations and depressions, with which the laminations are pressed together into a stack. This so-called linkage method is associated with several disadvantages:                a. The linkage technology requires the manufacture of very complex tools, whose parts are very sensitive in terms of material quality, and can be less robust than tools with which the laminations are not linked together. This increases both the costs and the risks associated with the method, which can hamper suitability for use.        b. Very thin steel sheets, e.g., those less than 0.35 mm thick, are very difficult to link, thereby resulting in inefficient methods.        c. Some products require that each lamination be turned by a specific amount. In a stack in which the laminations are not interlinked, the rotational angle is limited by the number of existing linkage locations, i.e., the smallest possible rotational angle is 90° given four existing linkage points.        d. Another disadvantage to the current linkage technology is that materials of varying thickness or characteristics (often distinguished by different quality designations) cannot be joined together.        
Other technologies that use externally applied adhesive have also been tried. Examples include DE 35 35 573 and DE 203 18 993, which both describe a method for using an adhesive that is applied to the band surface. An attempt has also been made to use capillary adhesive bonding, i.e., to run an adhesive “seam” down the outside edge of the stack.
Also known are methods (JP 2005 269 732) in which dots or lines of adhesive are applied to punched laminations. The adhesive is applied with an application head comprised of several nozzles.
In another method (JP 2001 321 850), the adhesive is sprayed onto the laminations at prescribed positions. The application unit provided for applying the adhesive has a distributor with three nozzles from which the adhesive exits.
The different existing technologies for applying adhesive to the band surface as an integrated part of core manufacture are associated with various difficulties:                a. The possible pressing rates are limited by how fast the adhesive is applied. For example, DE 203 18 993 defines speed ranges of up to 200-300 strokes per minute. Cost-effective core production requires that pressing rates measure at least 400 strokes per minute, with typical values in excess of 600 strokes per minute being highly desirable.        b. It is difficult to keep the tool clean. For example, a batch size limit of several thousand strokes is likely for one of the technologies, after which the tool has to be serviced and cleaned. The normal maintenance interval for a carbide tool lies at a minimum of 2,000,000 impacts. Shorter run times tangibly drive up the production costs.        c. Existing systems like those in DE 20 31 899 are known to have problems with component wear.(a), (b) and (c) all illustrate the fact that applying the adhesive depends on the contact between the application unit and strip.        d. The stacks fabricated with some adhesive bonding technologies can exhibit variable/unreliable stack strengths.        e. Tools with integrated application units can cost significantly more than standard tools.        f. The technology underlying the application system integrated into the tool can normally not be used in already existing tools.        g. In another known method (EP 1 833 145 A2), great success has been achieved in the contactless generation of lamination stacks with one application head per partial bond. One constraint on this method is the limited adhesive available for this method. This adhesive forms no long-term bond between the laminations under the thermal conditions for the normal range of application for such a lamination stack. Since the laminations are only partially bonded together with the adhesive, a high strength cannot be guaranteed. In addition, oscillations between the laminations cannot be prevented in some instances.        